There have been a few alternatives proposed to upgrade the water heating so that the long delays in getting hot water in the shower are eliminated:
Install mini-tank water heaters near each shower, sink or laundry room
pro: puts instant hot water where needed
con: electric, additional power consumed until central hot water is hot, one unit required in each bathroom, unless powered off, constantly using power to keep tank water hot
Install mini-tankless water heaters near each shower, sink or laundry room
pro: puts instant hot water where needed
con: electric, additional power consumed until central hot water is hot, one unit required in each bathroom, lowers water flow, most are 240v, large current draw
Install a circulating hot water pump and don't use the water until it shuts off
pro: only one unit required to cover all of upstairs bathrooms, unit can be turned on then will shut itself off when ready
con: delay in getting hot water after activating, not certain if advisable with Rinaii central tankless WH
Chili Pepper - very widely advertised for small home, small company, reasonably priced at $180 + s/h (Oct2008), 2 year warranty, X10 interface for remote control.
Grundfos - for professional installers in commercial and large home environments. Talk about $1000 minimum on site (Oct2008), 10 yr warranty on pump
iCirc - 5 year warrantee, "automatic", price not readily available other than by e-mail to inventor
RedyTemp - variety of products including one specifically for tankless water heaters, Digital programmable timer with one-shot override & remote control capability. $325 (Oct2008) Several sites report this unit is far better constructed, quieter, with included automatic timer or remote timer (such as X10), 2 yr warranty
ACT Metlund - similar to Chili Pepper design, $339 for smallest unit, up to $900 (Oct2008). 3 year warranty on pump.
List of others - list from tools web site, includes those above
Mini-tank water heater examples:
Mini-tankless water heaters:
Circulating hot water pumps"